Expand and collapse items

In List view, select an item and press Shift + ← to hide what is inside it, or Shift + → to show it again. Add Alt/Opt to do the same for every level inside.
Shift + Space — Expand or collapse the selected items
Shift + → — Expand the selected items
Shift + ← — Collapse the selected items
Shift + Alt/Opt + ← — Collapse every level inside
Shift + Alt/Opt + → — Expand every level inside
Shift + → expands one level: “Wireframes” stays collapsed until Shift + Alt/Opt + → expands everything inside “Website redesign”.